Composite aircraft



June 10, 1947.

' o. A. BUETTNER COMFOSITE AIRCRAFT Filed se t'. 3, 1943 2 Sheets-Sheet 1 rra 45UE7'T/YEP June 10, 1947.

, O. A. BUETTNER COMPOSITE AIRCRAFT I Filed Sept. 5, 1943 2 Sheets-Sheet 2 luvs/v7 OTTO/4.50577 I? A aewEy-v Patented June 10, 1947 UNITED STATES PATENT OFFICE COMPOSITE AIRCRAFT Otto A. Buettner, Pittsburgh, Pa.

Application September 3, 1943, Serial No. 501,089

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 3 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to aircraft and in general aims to provide a glider or gliding shell havin means to unite and lock it to a pair of airplanes so that the composit structure may be flown, and power means under operator control to release the airplanes quickly, so that each may pursue its course while the glider may bebrought to the ground without injury. Another object is to provide an aircraft composed of a glider and two airplanes, the composite wing of which is a fairly eificient airfoil. The glider of my invention may carry troops and/or supplies to a certain objective, or it may b nothing more than an expendable fuel tank, permitting two planes of short flying range to make ex.- tremely long flights, e. g. transoceanic flights, and when near their landing point to jettison the glider after drawing off the last of its fuel. My invention may also be useful in supplying isolated troops in areas which are unsafe for aircraft landings, since the gliders may contain large quantities of ammunition, food, medical supplies, etc. and may be caused to descend approximately where needed, while the airplanes may return to their starting point. Other objects of the invention are to provide a dependable locking and releasing mechanism for a composite aircraft of the character indicated, also to provide means which will improve the flying or gliding characteristics of the glider by minimizing drag. Further objects will be apparent from the following description of two embodiments of the invention shown in the accompanying drawings, wherein;

Fig. 1 is a perspective View of the glider per se;

Fig. 21s a top plan View of the composite flying structure composed of two complete airplanes with the glider of Fig. 1, one Wing of one airplane being omitted to expose the construction;

Fig. 3 is a front elevation of the flying strucre of Fig. 2;

Fig. 4 is a detail in sectional elevation of part of th mechanism for locking and releasing the airplanes;

Fig. 5 is a sectional view on a larger scale than Fig. 4 showing the locking means in locked position;

Fig. 6 is a view similar to Fig. 5 but showing the locking means in releasing position;

Fig. 7 is a detailin section showing how an inflatable bag fills a recess in the glider after the airplanes have been released therefrom; and

Fig. 8 is a plan view of another form of the invention.

The broad idea of a composite aircraft is disclosed in a number of patents of which Patents Nos. 1,546,442 to Glessner; 1,627,191 to Martin; and 2,308,764 to Makaroff are fairly representative. Also the pickaback plane concept, wherein a small plane takes off from the top of a large one of long flying radius, is shown in several patents, e. g. Mayo No. 1,925,768. In no prior patent or publication known to me has it been suggested that a glider be locked to one wing of two airplanes between which the glider is supported during flight, with means under the control of one or more pilots whereby the glider may be released in flight. Some of the manifold possibilities and advantages of this novel combination and arrangement of aircraft will be explained hereinafter.

Referring first to Figs. 1, 2 and a glider II is shown with fuselage l2, wings [3, vertical tail fin l4 and horizontal stabilizer I5. Elevators I 6, rudder I 1 and. ailerons I8 are also indicated, as well as a pilots compartment l9 and landing gear 20. In this instance the glider is a troop transport and has windows 2| and a door 22. The wings l3 are shown as having a smaller span than would be normally provided. for the glider, with substantially square tips. Extending inwardly from the glider wing tips; are recesses 23 which are open at the top, each recess 23 receiving the wing 24 of an airplane 25, preferably a monoplane of high power but limited flying radius, such as an interceptor or fighter.

The recesses 23 are each of such shape and depth as to fit snugly around substantially one entire airplane wing 24, with the top surfaces of the glider and airplane wings fairing into each other, and with square wing tips of the glider in contact with the fuselage 26 of the airplane. These wing tips may have curved end surfaces 21 which fit around and under the fuselages 26 as shown in Fig. 3. When two airplanes 25 are fitted on the glider, the leading and trailing edges of the glider wings respectively enclose the leading and trailing edges of the airplane wings in the recesses, the latter wings rising only slightly above the top surfaces of the glider wings. Furthermore, the glider wings have a sufficient taper so that they are only slightly wider at their tips than the chord of the airplan wings. The outer wings of the two airplanes form practically one continuous airfoil with the glider wings, as Figs. 2 and 3 clearly indicate.

With a high powered engine in each of the airplanes driving a variable pitch propeller of three or four blades (not shown), the described composite aircraft may take off from most runways and may fiy many thousandsofmiles since it is a-simple matter, with known-methods, to pump fuel from tanks (not shown) located in the glider to the tanks of the respective airplanes 25. The fuel conduits are not illustrated, but a fuel connection 30 (Fig. l) is indicated and this may be considered to be a quick-detachable connection of a well known type, permitting a parting of the fuel line'upon'apull or'stress on the same, practically without leakage at the connection because of an automatically closing valve. Communication between the two airplanes and between them and the-glider pilot may be had through an inter-communicating system of 'known'type (notshown) with-aiplug -31 at each tip of theghder wings making contact -w-ith-a -socket- (not shown) located on"theairplane. Other electrical connections -may be -rnade through thesame "or -similar;plug and =--socket connections, e. g. for radios, 'lightvsys- -tems, electriopower line etc. An inter-communicating system will permit the three pilots to coordinate their actionswhen turning, banking, climbing,- diving or-releasing the-airplanes. As the glider=has aileronsga rudder, and ele- 'vators, it may 'be controlled like the-airplanes. 'rlsmall engine (not shown) -may even be installed on the glider to rotate a; propeller to make possiblebetter control of the glider when cast loose by theairplanes near the point a where the glider is him landed.

-When bankingthe composite aircraft, the outer ailerons-28 of the two.-airplanes shouldxbe controlled in unison with the ailerons ill on the glider. However, the inner aiIerOnsZQ-on the airplanes are useless at this time, being wholly within'the -recesses 23. Asit is highly undesirable topre- 'ventop'erationof the inner'aileronsgsince'theairplanes "sh'ould'be releasable" at? anymoment, spe- "ciahrecessesSE areprovided toreceive the inner "ailerons andpermit ireea-ngular movement of the same simultaneously "with the useful "angular movement 'of the outena'ilerons-ifl. The-three rudders an'd" the' three sets of "elevators may, 'of

' course, be controlledfrom thethree p'ilotscompart-ments' without any difiicu-lty.

To-dock the two airplanes to the glider, several different mechanisms may be employed. The one illustrated in Figs-A; 5 and 6- comprises not only: i

looking and releasing means but also -power means for initially pushingapa'rt or forcibly separating the two locked wings as soon as they are :nnlocke'd. 'I he underside of the inner or lockable wing of each :ai'rplane has a pair-20f pivoted -L- shaped latches 49 depending I from lugs 4 I the endsofi said latches :engaging notchesnlzini the side wal-ls of a 'slidable sleeve 43-which is movable through the bottom wall' 'fl of-rec'ess' 23. At its upper endreach:sleeve='- 43 has a flange ii-which and tend to force thevl'atches automatically-outer the notches 42 when the withdrawn position of the keeper (Fig. 6) permits such action. A coil spring 5! surrounds the keeper and bears against an annular collar 52 fixed to the keeper nearits flexible springs 49 yield to the latches as they are moved upwardly out of the central bore 54 of the =sleevefresponsive to the separating of the airplane wing from its recess. An annular reinforc- "in'gc'olla'r'55,fixed to the glider wing, may surround the aperture 55 through which the sleeve slides and will provide a longer bearing for the sleeve.

'looperate-each sleeve to thrust an airplane wing upwardly and away from its recess when an airplanef isuto be. freedfrom:thezglidenwa toggle :linkageiis providdptogether wvith 1a: servomotor to expand and :contract :the linkage, zthe rentire mechanism preferably being .2 located inside the glider wing ::beneath the recess 1: 23. :Reversible -servom-otorr56 (which mayxber fixed to a'iwing rib -or spar, not :shown) rotateszra lead vscrew r51 2 through reductiomgearing: enclosed :lins. gear:,.-box- -58, The switches sand .circuits, :by -"Which oneasor more .operatorsl controlthe rotationz0fzthezservo- '=moto1s, are not shown because theyzare cconventional. TWoiImtsf159,ESELtraVelfibaCk andiforth on 1 the lead -screw,:whic'h :is held: againsts'axial movement. 2 Pivoted--to:.-ni-it:5Ftaretwov links 6 l 62 while nut likewise: is pivotally rconnected l'wit'h two links '63; 64. Links 6 Iiand-63:areialsorpivotediat their' othenen'ds':toi zfiangezfiSfintegral withithe slidablei sleeve, while links;62,': 64,: are; pivotedsat -.their other 'ends' to an. anchoring. ring:66, which fmay ibe :riveted 5170 the glider x-wi'ng. The .:de- :scribed arrangement'w ill give theiservomotonme- 'cl'ianicaladvantage to thrust the sleeveiupwardly withl great force: and iwithisuifici'ent'zspeedi totinsure quick parting: of i the. twoiwingsiiaszsoonrias the latches are: disengaged. sArwirecablei 61; fast I to the lower end m: thefkeeper; igssecurediatiits othenendz-toa non-rotating sleeve 68surrounding f the lead: screw; which thusprovides ananchortfor the cable. As theltoggle linkage expands, i. e.;.as nuts 59$60 approach eachiothenzsleevei43:.eis first movedsupwardl .aand fthen the: iinextensiblescable B1 separates the-keeper: frommheaupwarmyimo ing. latches, whereupon theticoilisprin'gss-forc lthe l'latches 'out of the notches 42 asal-readyiexplained. Preferably: there will :beztwo ewinge'locking mecheanisms :as desciibed *for releasably secuiin san airplane wing: to ma Eglider swing; 3'1'l0WeVBI,I lJ 'is within the scope of the present inventionctmde :sign the recesses 23gan'dthe-airplane'wingszwhich fit' into them, incsucha' eway' thatz the --wingss.are partially: locked: by sinter-fittingesurfaces; =for; in-

stance alongthe leading'redges of thevairplane wings, "and complete locking3;is-;obtained bycemploying only one toggle linkage mechanism. When thecomposite aircraft issin full flight-Where will be powerful forces tendin to holdtheiocked wingstogethen-esince; frequentlyhp to l0% of;:,the lift 'arises from negative,v :pressure on the toprsurfaces of an airfoil, and this negative pressura'will tend: toi hold the; juxtaposed wingstogetherwven --without latching*means. It 'will bezaappre'ciatd, however, that when banking, climbing, divin i or turning, some forml-of' dependable locking .means is essential.

1 To fill: the: recesses f23xso ithat'tthe :glidemmay have good gliding characteristics, an inflatable bag (Fig. '7) may be fixed, for example by cement, to thebottom of each recess between the wing locking means, and the shape of these bags may be such that when inflated each bag almost completely fills a recess with its upper surface fairing with the top surface of the glider wing. Rubber or certain rubber-like plastics may be used to make these bags, and carbon dioxide gas, under pressure in a valved bottle H (which may be held on the glider wing adjacent the recess) may blow up the bags. A very simple valve arrangement (not illustrated) may automatically open the bottle II to start inflation as soon as the airplane wing moves out of its recess, the valve being opened by a lever 73 moved by sleeve 43 as it nears its upper limit of movement, shown in Fig. 6. Apertures (not shown) may be formed in the inflatable bag to permit movement of sleeves 43 and separation of the latches 40 from said sleeves, as above described. The arrangement of Fig. 7 is omitted from other figures of the drawings because it is a constructional detail which is not essential.

Now referring to Fig. 8, a glider I5 has two airplanes 1'6 alined spanwise as in Fig. 2, and secured by locking means (not shown) to permit the com- .ponent parts of the aircraft to fly as one airfoil and yet be releasable from each other when desired. A pair of twin booms 11 extend forwardly of the leading edge of theglider airfoil parallel to each other and at equal distances from the central axis of the glider. Secured to the forward ends of booms TI is a horizontal stabilizer l8 having spaced vertical stabilizers 19 which may have the usual rudders (not shown) hinged adjacent their trailing edges. The pilot may sit in a small cabin at. the nose 80. I prefer this form of glider because it will be more stable and will have better gliding characteristics.

In some instances it may be desirable to employ a towing plane to help lift the loaded composite aircraft off the ground, with controlled disengagement of the towing line once the aircraft is flying at a safe speed, as is known in the art of gliders. While releasing of the airplanes by the airplane pilots was described, where the glider has a pilot it may be desired to operate the wingreleasing mechanisms simultaneously from a station in the glider cabin. Also, it has been assumed that the airplanes are to be released before the glider descends to the ground, but if preferred the composite airplane may land without disengagement of the locked wings, wherever a paved runway of suificient length is available. By designing the glider wings properly, there will be suflicient room inside each wing for men to crawl during flight from the glider wing tips through trap doors (not shown) and over the airplane wings to the airplane cabins or cockpits, if means are provided on the airplane wings to afford hand holds. Movement of personnel in the other direction will be no more difficult.

The described aircraft will make it possible to deliver two airplanes of short flying radius to the most distant and inaccessible regions of the world. The glider may deliver personnel and/or supplies at any point, or if military necessity requires, it may be jettisoned at any time. If the composite aircraft arrives over an area where friendly troops are advancing against the enemy, the glider may be brought to the ground to supply the troops or an advanced air field, and the airplanes. freed of their burden and with a full load of fuel, may proceed to attack the enemy before landing at the air fleld. If the glider is made buoyant, with pontoons or amphibian landing gear instead of the wheels illustrated in Fig. 3, landings may be made on water under favorable conditions. Other possible uses of the described aircraft will occur to military and naval personnel.

What I claim is:

1. In a motorless monoplane glider adapted to be carried aloft bya pair of powered monoplanes with the fore and aft axes of all three aircraft lying parallel and having the same directional orientation, said monoplane glider comprising a fuselage and right and left wing sections, said Wing sections each being provided with a' recess in the top surface thereof extending through the wing tip and toward the said fuselage for a distance sufficient to accommodate substantially an entire wing section of one of said powered monoplanes therein, complementary detachable connecting means carried on the underside of the wing sections of said powered monoplanes and in the recessed portions of the said monoplane glider wing sections for securing one wing section of each of said pair of powered monoplanes to one each of said monoplane glider wing sections with the central fore and aft axis of each powered monoplane lying adjacent to the opposite wing tips of the said monoplane glider, release of said complementary detachable connection means releasing said monoplane glider from said powered monoplanes for independent airborne operation.

2. In a motorless monoplane glider adapted to be carried aloft by a pair of powered airplanes with the fore and aft axis of all three aircraft lying parallel and having the same directional orientation, said monoplane glider having opposed wing sections with control surfaces thereon, each said wing section being provided with a recess in the top surface thereof extending through the wing tip and inwardly along the wing section for a suflicient distance to accommodate substantially an entire wing of a powered airplane, each said recess having an aileron slot along a portion of the periphery thereof for permitting aileron operation of attached powered monoplanes, an inflatable bag in each said recess adaptable to be inflated to substantially fill the said recess to give gliding characteristics to the monoplane glider, thrust producing means operable for thrusting a powered airplane wing out of said recess, and detachable connection means operatively connected with the said thrust producing means in the said recess for securing a powered airplane wing within said recess adaptable upon the said thrust producing means thrusting a powered airplane wing out of said recess to detach the said detachable connection means.

3. In a composite aircraft; a motorless monoplane glider having a fuselage and wings with control surfaces thereon facilitating guiding thereof; the said monoplane glider wings being provided with a recess in the top surface thereof extending through the wing tip and toward the said fuselage for a sufficient distance to accommodate substantially an entire wing of a powered monoplane, each said recess having an aileron slot along a portion of the periphery thereof; a collapsed inflatable bag secured to the bottom wall of each said recess adaptable to be inflated to substantially flll the said recess; a powered monoplane on opposite sides of the said monoplane glider and having the same directional orientation with their wings arranged spanwise with the monoplane glider wings, the adjacent said inflatable bag to give gliding characteristics 15 tothe said monoplane glider, I M OTTO A. BUET'I'NER.

7 BEFERENCES'CITED The following references are of recordin the file of this patent:

STATES PATENTS Number Name I Date 1,753,227 Dornier Dec. 2, 1930 1,628,098 Abreu- May 10, 1927 1 1,650,346 Hall NOV. 22, 1927 997122 Fen'n July'4, 19-11 FOREIGN PATENTS Number Country Date 731,9ll France June @1932 546,587 Great Britain July 20, 1942 

